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Date: Tue, 13 Jan 2009 15:26:09 -0500
From: "Kyle Moffett" <kyle@moffetthome.net>
To: "Christian Borntraeger" <borntraeger@de.ibm.com>
Subject: Re: current git kernel has strange problems during bisect
Cc: "Linus Torvalds" <torvalds@linux-foundation.org>,
       "Sam Ravnborg" <sam@ravnborg.org>,
       "Johannes Schindelin" <Johannes.Schindelin@gmx.de>, git@vger.kernel.org,
       "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
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On Sun, Jan 11, 2009 at 4:39 PM, Christian Borntraeger
<borntraeger@de.ibm.com> wrote:
> In my opinion we should really avoid subtree merges in the future as a curtesy
> to people who do the uncool work of testing, problem tracking and bisecting.
> </rant>

As an alternative, you can relatively easily rewrite the following
independent histories:

A -- B -- C
X -- Y -- Z

To look like this:

A -- B -- C -- X' -- Y' -- Z'

Where X' is (C + sub/dir/X), Y' is (C + sub/dir/Y), etc...

Assuming the following:
  "master" branch points to commit C
  "child" branch points to commit Z
  "${KIDSTART}" is the SHA1 id of commit X

echo "${KIDSTART} $(git rev-parse --verify master)" >>.git/info/grafts

git filter-branch --index-filter 'git read-tree master && git
read-tree --prefix="sub/dir/" "${GIT_COMMIT}"' -- master..child

The one downside is then somebody actually has to *test* those commits
when doing a bisect, even though they did not materially change
anything.  The upside is that there isn't any "what the hell just
happened?" when you *do* end up in the newly-created branch.

Cheers,
Kyle Moffett
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